EmptyIterator


1   /**
2    * Dream
3    * Copyright (C) 2003-2004 INRIA Rhone-Alpes
4    *
5    * This library is free software; you can redistribute it and/or
6    * modify it under the terms of the GNU Lesser General Public
7    * License as published by the Free Software Foundation; either
8    * version 2 of the License, or (at your option) any later version.
9    *
10   * This library is distributed in the hope that it will be useful,
11   * but WITHOUT ANY WARRANTY; without even the implied warranty of
12   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
13   * Lesser General Public License for more details.
14   *
15   * You should have received a copy of the GNU Lesser General Public
16   * License along with this library; if not, write to the Free Software
17   * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
18   *
19   * Contact : dream@objectweb.org
20   *
21   * Initial developer(s): Matthieu Leclercq
22   * Contributor(s): 
23   */
24  
25  package org.objectweb.dream.util;
26  
27  import java.util.Iterator  ;
28  import java.util.NoSuchElementException  ;
29  
30  /**
31   * An empty iterator implementation. The {@link #hasNext() }method always
32   * returns <code>false</code>. The constructor is private. As a consequence,
33   * only one instance of this class exists, and can be referenced using the
34   * {@link #INSTANCE }constant.
35   */
36  public final class EmptyIterator implements Iterator  
37  {
38  
39    /** The only instance of <code>EmptyIterator</code> */
40    public static final EmptyIterator INSTANCE = new EmptyIterator();
41  
42    private EmptyIterator()
43    {
44    }
45  
46    /**
47     * @see java.util.Iterator#remove()
48     */
49    public void remove()
50    {
51      throw new IllegalStateException  ();
52    }
53  
54    /**
55     * @see java.util.Iterator#hasNext()
56     */
57    public boolean hasNext()
58    {
59      return false;
60    }
61  
62    /**
63     * @see java.util.Iterator#next()
64     */
65    public Object   next()
66    {
67      throw new NoSuchElementException  ();
68    }
69  
70  }
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